I. Field of the Invention
Certain aspects of the present disclosure generally relate to duplexers used in radar systems for simultaneously transmitting and receiving signals, and more particularly, to a cancellation circuit to cancel leakage signals.
II. Description of the Related Art
In one aspect of the related art, a wireless transceiver system may be used for millimeter wave communications, such as the systems envisioned in the Institute of Electrical and Electronic Engineers (IEEE) 802.11.ad and IEEE 801.15.3c standards, and the Wireless Gigabit Alliance (WGA). The PHY layer may be configured for millimeter wave communications in the spectrum of 57 to 66 gigahertz (GHz), or Ultra Wide Band (UWB) communications in the spectrum of 3.1 to 10.6 GHz.
In another aspect of the related art, such transceiver systems may be used for radar applications. The transceiver emits a waveform comprising a single pulse, a sequence of pulses, or a continuous waveform having a finite duration. The waveform may be transmitted periodically at a predetermined interval. A transmitted signal is scattered by a target of interest, and a reflected signal returns to the transceiver, where it is amplified, down-converted, digitized, and then processed to obtain the target's parameters.
Nearby targets, referred to as clutter, typically do not include targets of interest. Backscatter from clutter produces strong echoes with very small delays. For example, a target at 3 m from the transceiver produces a reflected signal at 20 ns. If the transceiver shares a single antenna for both transmit and receive operations, a high-speed switch would need to be employed. However, such switches are costly and difficult to implement. Furthermore, full-duplex systems often suffer from insufficient isolation of the receiver from the transmitter, resulting in a substantial leakage signal.